1. Field of the Invention
This invention relates generally to compositions, methods and apparatus used for use in the manufacture of semiconductor, photovoltaic, LCF-TFT, or flat panel type devices. More specifically, the invention relates to methods and compositions for utilizing a metal bis-β-diketiminate precursor.
2. Background of the Invention
Controlling the atomic layer growth is one of the ultimate goals for the semiconductor industry. Copper has displaced aluminum to become the standard back-end-of-line (BEOL) metallization material for advanced logic devices. Copper's benefits over aluminum for logic are now well-documented. Its lower resistivity allows line thickness to be reduced by nearly one-third while achieving similar sheet resistance (as aluminum). Ta/TaN liner/barrier and Cu seed layer are usually deposited using Ionized Physical Vapor Deposition (iPVD) and trenches may be filled with Cu by Electro-Chemical Deposition (ECD). One limitation inherent with this process is the non-conformality of the deposition of Cu by iPVD.
The formation of copper containing films via Chemical Vapor and Atomic Layer Deposition (CVD and ALD) are promising. CVD and ALD are the main gas phase chemical process used to control deposition at the atomic scale and create extremely thin and conformal coatings. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or decompose on the substrate surface to produce the desired deposit. ALD process are based on sequential and saturating surface reactions of alternatively applied metal precursor, separated by inert gas purging.
For process reasons, deposition of copper would be best realized at low temperature, below 150° C., which makes deposition of copper particularly challenging. To overcome this difficulty, some have used a surface activating agent (pyrazole for instance) to enable the deposition of copper using copper bis-β-diketiminate precursors on metal surface at low temperature. Nevertheless direct deposition of copper on the semiconductor substrate remains impossible in a classical thermal CVD or ALD process.
Furthermore, metal silicide layers are a useful material in transistors to improve the conductivity of polysilicon. For instance nickel silicide (NiSi) or cobalt silicide (CoSi2) may be used as a contact in the source and drain of the transistor to improve conductivity. The process to form metal silicide begins by the deposition of a thin transition metal layer, nickel for instance, on the polysilicon. The metal and a portion of the polysilicon are then alloyed together to form the metal silicide layer. In theory, a thin layer of pure metal could be produced using CVD or ALD process but, the process could fail if the precursor has too much thermal stability.
PEALD and PECVD are promising techniques to produce high purity and high-density metal thin films even at low growth temperatures. During a plasma process, plasma is introduced during the reactant pulse step of each cycle to activate the reducing gas, which will further react with the surface species. PEALD and PECVD process have never been considered so far for the deposition of metal films using metal bis-β-diketiminate precursors.
Consequently, there exists a need for metal bis-β-diketiminate precursors, and methods of their use in deposition processes for creating a thin film.